Heat the oil in a large saucepan over medium heat. Add the onion and cook until softened, about 5 minutes. Cut the squash into 1/4-inch dice and add to pot along with the potato. Stir in the stock and bring to a boil. Reduce heat to low, cover and cook 20 to 30 minutes or until vegetables are tender. Remove the lid, add the beans and all but the 1/4 cup of corn and cook 15 minutes longer to thicken and blend flavors. Stir in the soy milk and simmer about 5 minutes to blend flavors. Remove from the heat. Transfer up to 2 cups of the soup to a food processor or blender and puree until smooth. Stir the puree back into the chowder and season to taste with salt and pepper. Ladle the soup into bowls and garnish with the reserved corn kernels and the parsley.